<!DOCTYPE html>
<title>Reference of testcases for background-position-x animations</title>
<style>
#test {
  height: 100px;
  width: 100px;
  background-repeat: no-repeat;
  background-image:url(); /* a 25x25 px red box */
  background-position-x: 50%;
}
</style>
<div id="test"></div>
